Surgical guidance and planning software for astigmatism treatment

ABSTRACT

Software for calculating an astigmatism treatment is operable upon execution to perform the following steps: receiving biometric information for a patient; determining based on the biometric information an astigmatic correction comprising at least one of (a) a position for one or more limbal relaxing incisions and (b) a power and an orientation for a toric intraocular lens (IOL); generating an output comprising the astigmatic correction; receiving a selection of a different ratio of astigmatic correction attributable to the one or more limbal relaxing incisions and the toric IOL; determining an updated astigmatic correction including at least one of (a) an updated position for the one or more limbal relaxing incisions and (b) an updated power and/or orientation of the toric IOL.

This application is a divisional of U.S. Non-Provisional applicationSer. No. 14/312,187 filed Jun. 23, 2014, which claims the priority ofU.S. Provisional application No. 61/836018 filed Aug. 7, 2013.

TECHNICAL FIELD

The present invention relates generally to surgical guidance andplanning software for astigmatism treatment, and more particularly, to amethod and system for determining astigmatism treatment with toricintraocular lenses and incisions.

BACKGROUND

The human eye functions to provide vision by refracting light through aclear outer portion called the cornea, and refracting the light by wayof a crystalline lens onto a retina. The quality of the focused imagedepends on many factors including the size and shape of the eye, and thetransparency of the cornea and the lens. When age or disease causes thelens to become aberrated, vision deteriorates because of the loss ofretinal image quality. This loss of optical quality in the lens of theeye is medically known as a cataract. An accepted treatment for thiscondition is surgical removal of the lens and replacement of the lensfunction by an artificial intraocular lens (IOL).

In the United States, the majority of cataractous lenses are removed bya surgical technique called phacoemulsification. During this procedure,a portion of the anterior capsule is removed and a thinphacoemulsification cutting tip is inserted into the diseased lens andvibrated ultrasonically. The vibrating cutting tip liquefies oremulsifies the nucleus and cortex of the lens so that the lens may beaspirated out of the eye. The diseased nucleus and cortex of the lens,once removed, is replaced by an artificial lens in the remaining capsule(in-the-bag). In order to treat corneal astigmatism, the IOL may betoric. The power selection for the IOL can also take into account theeffect of incisions in the corneal shape (astigmatism) through which theIOL is injected, as described in greater detail in U.S. Pat. No.7,476,248, which is incorporated herein by reference.

An alternative treatment for corneal astigmatism is the use of limbalrelaxing incisions (LRIs), which are typically opposed arcuate incisionsin the cornea that reshape the cornea to correct astigmatism. While theterm “limbal relaxing incision” or “LRI” is used in this specification,because the incisions are typically made at the limbus and thereforeconventionally described this way, the term should be understood toinclude any corneal relaxing incision, referring generally to anyincision that does not penetrate the cornea and that is positioned toadjust the astigmatism of the cornea. Based on statistical samples ofsurgical outcomes, two commonly used nomograms, the Donnenfeld nomogramand the Nickamin nomogram, have been developed to guide surgeons inperforming LRIs. The Donnenfeld nomogram takes into account age(relatively to average age for cataract patients), incision location andpattern, and whether the astigmatism is with the rule or against therule. The Nickamin nomogram considers age and degree of astigmatism moregranularly than the Donnenfield nomogram. These nomograms can be furthercustomized based on the surgeon's actual surgical outcomes.

SUMMARY

In a first embodiment, software for calculating an astigmatism treatmentis operable upon execution to perform the following steps: receiving aninitial primary incision position; determining a power and orientationfor a toric intraocular lens (IOL) to treat an astigmatism of an eyebased on the initial primary incision position; determining an adjustedprimary incision position based on the power and the orientation for thetoric IOL to further reduce the astigmatism; and generating an outputcomprising the adjusted primary incision position.

In a second embodiment, software for calculating an astigmatismtreatment is operable upon execution to perform the following steps:receiving biometric information for a patient; determining based on thebiometric information an astigmatic correction comprising at least oneof (a) a position for one or more limbal relaxing incisions and (b) apower and an orientation for a toric intraocular lens (IOL); generatingan output comprising the astigmatic correction; receiving a selection ofa different ratio of astigmatic correction attributable to the one ormore limbal relaxing incisions and the toric IOL; determining an updatedastigmatic correction including at least one of (a) an updated positionfor the one or more limbal relaxing incisions and (b) an updated powerand/or orientation of the toric IOL.

Of course, those skilled in the art will appreciate that the presentinvention is not limited to the above features, advantages, contexts orexamples, and will recognize additional features and advantages uponreading the following detailed description and upon viewing theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example system suitable for use with variousembodiments of the present invention;

FIG. 2 illustrates a flow chart for providing a predicted astigmaticcorrection with an optimized LRI position;

FIG. 3 illustrates a flow chart for providing an optimized primaryincision location;

FIG. 4 shows a flow chart 400 for providing interactive calculation ofastigmatism treatment using toric IOLs and incisions; and

FIGS. 5-10 illustrate an example GUI incorporating all three of theexamples presented herein.

DETAILED DESCRIPTION

Various embodiments of the present invention provide improved methodsand systems for surgical planning that advantageously addresses bothtoric IOL power and incisions. In particular, these methods and systemscan use predict a combined treatment to reduce the overall astigmatismin the post-surgical patient's overall optical system more nearly tozero. The output provided by these systems will be referred to herein asa “predicted astigmatic correction” to indicate that this would be theexpected correction produced by the combination of incisions and/or thetoric IOL. When the term “optimized” is used in the context of thisdescription, it refers to the surgical astigmatism being reduced asnearly to zero as possible within the range of the treatment parametersthat are being varied within given ranges. This may be influenced, forexample, by the restrictions given by the surgeon, who may prefer tomake incisions on one side or within one quadrant, thus restricting theavailable range of incision locations. These may also be influenced bythe increments of cylindrical power in which a selected toric IOL areavailable, so that, for example, the toric IOL selection must be made inhalf-diopter increments.

In certain embodiments, methods and systems for surgical planning mayprovide integrated surgical planning that provide a combined calculationfor both toric IOL and LRI calculations. In other aspects, methods andsystems for surgical planning may provide options to allocate a certaindegree of astigmatism correction to each component of the astigmatictreatment, allowing the surgeon to select from a variety of treatmentoptions using different toric IOLs and LRI techniques. Such options mayinclude varying the length, depth, position and/or number of LRIs aswell as the power and orientation of the toric IOL. In still otheraspects, methods and systems for surgical planning may receive a primaryincision and secondary incision locations, referring to the incisionthrough which the IOL will be inserted as well as irrigation, aspirationand other instruments necessary for the cataract operation, and then maydetermine a combination of toric IOL power and orientation along with anadjusted incision placement so that the combination of the toric IOL andthe incisions provide an improved treatment.

As described herein, any such methods and systems can be implemented insoftware, hardware, and/or firmware, and the various functions can bedistributed among multiple components, such as biometers for collectingpatient information and ophthalmic surgical equipment used inperformance of surgical procedures for correcting astigmatism (includingbut not limited to surgical microscopes and laser systems for incisingthe cornea, lens capsule or crystalline lens). Implementations may alsoinclude the use of programmable electronic computing devices, such asdesktop or laptop personal computers, electronic tablets, personaldigital assistants, or smart phones, loaded with appropriate software.It should therefore be understood that the various examples describedherein can be suitably modified in numerous other usable combinations.

FIG. 1 illustrates an example system 100 suitable for use with variousembodiments of the present invention. System 100 includes a processor102, a memory 104, an interface 106, a biometer 108 and surgicalequipment 110. Processor 102 may be any microprocessor, microcontroller,programmable element, or other device or collection of devices forprocessing electronically stored instructions (software or firmware) toperform any of the various information processing functions describedherein. Memory 104 may be any suitable form of volatile or non-volatileinformation storage accessible by processor 102, including but notlimited to optical, electronic, or magnetic media. Interface 106represents any electronic component allowing exchange of informationwith a person (referred to herein as a “user” of system 100) or betweenthe components of system 100. User interfaces suitable for communicationwith persons may include any known input device for computers, includinga touch screen, keyboard, switch, knob, pedal, button, pointing device,or other similar component. Interface 106 may likewise include anysuitable visible and/or audible output, such as a monitor and/orspeaker, for communication of information to the user, which may displaya graphical user interface (“GUI”) to allow the user to operate system100. Interface 106 may also include any suitable electronic componentsfor exchanging information with other electronic devices (includingwireless signals), such as other components of system 100, according toany programmed information exchange protocol.

Biometer 108 is any suitable device for taking anatomical measurementsof a patient's eye using, for example, optical or ultrasoundmeasurements. Such anatomical measurements may include withoutlimitation the axial length of the eye, anterior chamber depth,crystalline lens thickness, corneal diameter (white-to-white distance)and the anterior and/or posterior curvature of the cornea. Surgicalequipment 110 may include any form of equipment suitable for use inperforming surgical procedures for the correction of astigmatism thatincludes suitable electronic components for intercommunication withother components of system 100, including but not limited to surgicalmicroscopes and laser systems for incising the cornea, lens capsule orcrystalline lens.

Code 120 represents instructions stored in memory 104 executed byprocessor 102 to perform various functions of system 100. As notedpreviously, various embodiments of the present invention provideimproved methods and systems for surgical planning that include bothtoric IOLs and incisions. Thus, in operation, various embodiments of thesystem 100 include techniques for planning surgery capable of addressingastigmatism based on certain information. Patient information 122represents all stored information concerning the astigmatism treatmentfor a specific patient, which may include, without limitation, biometryinformation taken from biometer 108 and surgeon-specific informationthat may be stored from previous surgical planning or may be input aspart of the planning process.

Example 1

In one example of a method of operation, FIG. 2 illustrates a flow chart200 for providing a predicted astigmatic correction with an optimizedLRI position. In general, system 100 may determine LRI position based onmultiple additional aspects of the patient as compared to prior nomogramtechniques. At step 202, system 100 receives via interface 106 (orcalculates from stored information) the following six parameters: (1)the astigmatism to be treated, (2) the axis of astigmatism, (3) patientage, (4) a surgeon-specific treatment zone (radial location of theincision), (5) a surgeon-specific LRI depth as a percentage of thepatient's maximum corneal thickness, and (6) the patient specificcorneal power. For purposes of this specification, “receives” in thecontext of patient-specific information shall refer generically both toreceiving information from a user or from another device via theinterface as well as deriving or calculating the specified informationfrom other information that has been received in this manner. Theserepresent a minimum number of factors to be considered, but additionalfactors can be added to the determination. For example, the location ofthe primary incision and/or any secondary incisions, including radialand angular location and angular span (arc length), can also beconsidered.

At step 204, system 100 then outputs a predicted incision location forone or more LRIs that reduces the astigmatism as nearly to zero aspossible given the expected resolution of the incision placement. Inparticular embodiments, the predicted incision location may also varyone or more of the angular span (arc length), radial position, andnumber of incisions. In certain embodiments, the relative arc length,number or arrangement of the incisions can be adjusted so that; forexample, the arc length of one incision may be larger than that of anopposed incision. A factor of 1.5-2.0 in particular may be useful forbalancing the relative effects of the opposed LRIs. In certainembodiments including calculations of the primary incision, the primaryincision location can be adjusted, and the predicted incision locationcan also be updated based on the adjusted primary incision. Empiricalstudies and additional surgeon-specific results can further tailor theresulting nomogram for a particular system 100 and particular surgeon sothat the predicted incision information can more accurately minimize therelevant astigmatism. This is illustrated at step 206, wherein system100 stores surgical outcome information correlated with the predictedincision location.

Example 2

In a second example, FIG. 3 shows a flow chart 300 for providing anoptimized primary incision location. At step 302, system 100 receives aprimary incision location, which may include radial and angular positionas well as surgeon-specific factors such as a predicted surgicallyinduced astigmatism. At step 304, system 100 determines the astigmatismto be corrected for the patient, which may be based on calculations madeby system 100 from patient biometry measurements or which mayalternatively be information about a selected toric IOL that has beenpreviously calculated. Based on the initial primary incision location,at step 306, system 100 determines an adjusted incision location and/ortoric IOL position so that the astigmatism is reduced relative to theinitial primary incision location. This results from the surgicalastigmatism that is produced by the primary incision being changed, sothat the net effect of the toric IOL and the surgically inducedastigmatism from the primary incision can more nearly reduce the netpost-surgical astigmatism in the patient's optical system to zero.

In alternative embodiments, the user can input the different primaryincision location, and system 100 can calculate an updated toric IOLpower and position in response to the input. In some embodiments, thepower of the toric IOL may also be adjusted based on the incrementalcylindrical power steps for the selected toric IOL. Thus, for example,it might be more advantageous to use a toric IOL with less cylindricalpower or with a different orientation if the adjusted primary incisionlocation provides a greater degree of astigmatism correction.

At step 308, system 100 outputs an adjusted surgical plan with theadjusted primary incision position and the adjusted toric IOL positionand/or power, if applicable. If LRIs are also a component of theastigmatism treatment, then these incision positions may also beupdated, including angular position, angular span (arc length), radialposition, and/or number of incisions. In certain embodiments, therelative arc length, number or arrangement of the incisions can beadjusted so that; for example, the arc length of one incision may belarger than that of an opposed incision. A factor of 1.5-2.0 inparticular may be useful for balancing the relative effects of theopposed LRIs. In general, system 100 can optimize the surgical planthrough a combination of toric IOL power and orientation, primaryincision placement, and LRI placement to reduce astigmatism as close tozero as possible.

Example 3

In a third example, FIG. 4 shows a flow chart 400 for providinginteractive calculation of astigmatism treatment using toric IOLs andincisions. At step 402, system 100 receives initial primary incisioninformation, which may include radial and angular position informationas well as surgeon-specific factors such as a predicted surgicallyinduced astigmatism. At step 404, system 100 generates an initialsurgical plan. The surgical plan includes a radial location for theprimary incision and one or more LRIs as well as a toric IOL power andorientation. At step 406, system 100 receives a user selection of adifferent ratio of astigmatism treatment between the toric IOL and theLRI. For example, the user may select a certain percentage of thepatient's astigmatism to be corrected by the IOL and the remainder to becorrected by the LRIs. Alternatively, the user could consider caseswhere the astigmatism would be entirely corrected by either the IOL orthe LRIs. At step 408, system 100 determines an adjusted surgical planbased on the different ratio, and then outputs the adjusted surgicalplan at step 410. In certain embodiments, the relative arc length,number or arrangement of the incisions can be adjusted so that; forexample, the arc length of one incision may be larger than that of anopposed incision. A factor of 1.5-2.0 in particular may be useful forbalancing the relative effects of the opposed LRIs.

Importantly, the foregoing examples are not intended to be exclusive ofone another. For instance, all three examples can be implemented withthe formula of the first example. Likewise, all three examples canadjust primary incision locations, and all three examples can allow foradjustment of the ratio of astigmatism correction between the toric IOL,primary incision, and LRIs. Thus, these features should not beunderstood as exclusive of one another.

Software Interface

FIGS. 5-10 illustrate an example GUI incorporating all three of theexamples presented herein. While this example is not based on values foran actual patient, the operation is illustrated in the same manner as itwould be for an actual patient. In FIGS. 5-10, the six parametersprovided in the first example are illustrated with correspondingnumbers. FIG. 5 shows an example LRI-only treatment based on the sixpatient factors. The predicted incision location includes an angularlocation and span (arc length) for the LRIs. FIG. 6 illustrates anadjustment in the primary incision location, which in turn adjusts thesurgically induced astigmatism and the LRI position. In FIGS. 5-6, onlyLRIs are being used to treat astigmatism; the IOL is not toric.

FIGS. 7-10 illustrate a “slider bar” input allowing the user to select adifferent ratio between the astigmatism treatment provided by the toricIOL and LRIs. This is one of any number of possible examples for the GUIfor selection of the ration, including without limitation numericalentry fields (which may also include up/down arrows), knob icons, radiobuttons with specified ratio increments (e.g., cylindrical powerincrements for the toric IOL), or any other conceivable GUI interfacefor adjustment of the ratio. In FIG. 7, the treatment provided is 100%attributed to the toric IOL, taking into account the surgically inducedastigmatism of the primary incision. The toric IOLs are denominated asSN6ATx, where x increases with the amount of cylinder power (TO beingzero cylindrical correction, i.e., a non-toric IOL). The residualastigmatism in this case is 0.24 diopters at 14 degrees based on aselection of the toric IOL model resulting in the lowest residualastigmatism.

In FIG. 8, the slider bar has been adjusted so that the ratio ofastigmatism treatment is only 66.07% attributable to the toric IOL, andthe adjusted surgical plan includes LRI positions to correct theremaining 33.93% of the patient's astigmatism. A lower power toric IOLmodel has been selected, and now the residual astigmatism with the LRIsis zero. In FIG. 9, the ratio is adjusted to increase the percentageattributable to the LRIs, producing an increase in the angular span (arclength) of the LRIs and a further reduction in the toric IOL power. Thisagain results again in zero astigmatism. Lastly, in FIG. 10, over 70% ofthe correction is attributable to the LRIs, producing an even lowertoric IOL power with slightly longer LRIs. Note that even a non-toricIOL results in only 0.70 diopters of residual astigmatism, illustratingthat almost all astigmatism correction results from the LRIs.

The preceding description of various embodiments was given for purposesof illustration and example. Those skilled in the art will appreciate,of course, that the present invention may be carried out in other waysthan those specifically set forth herein without departing fromessential characteristics of the invention. In particular, features ofthe various embodiments are intended to be freely combined with oneanother in any combination, unless the features are explicitly orapparently exclusive of one another, and any such features can begeneralized to any level of intermediate combination. The presentembodiments are thus to be considered in all respects as illustrativeand not restrictive, and all changes coming within the meaning andequivalency range of the appended claims are intended to be embracedtherein.

What is claimed is:
 1. Software embodied in a computer-readable mediumand operable upon execution by at least one processor to perform thefollowing steps: receiving biometric information for a patient;determining based on the biometric information an astigmatic correctioncomprising at least one of (a) a position for one or more limbalrelaxing incisions and (b) a power and an orientation for a toricintraocular lens (IOL); generating an output comprising the astigmaticcorrection; receiving a selection of a different ratio of astigmaticcorrection attributable to the one or more limbal relaxing incisions andthe toric IOL; determining an updated astigmatic correction including atleast one of (a) an updated position for the one or more limbal relaxingincisions and (b) an updated power and/or orientation of the toric IOL.2. The software of claim 1, wherein the selection of the different ratiois entered by the user via a slider bar displayed on a graphical userinterface of the software.
 3. Software embodied in a computer-readablemedium and operable upon execution by at least one processor to performthe following steps: receiving the following information for a patienthaving astigmatism: (a) an astigmatism value to be treated, (b) an axisof the astigmatism, (c) a patient age, (d) a radial location of at leastone limbal relaxing incision, (e) a depth for the at least one limbalrelaxing incision, and (f) a corneal power for the patient; determiningat least one limbal relaxing incision position based on all of theinformation (a)-(f); and generating an output comprising the at leastone limbal relaxing incision position.
 4. The software of claim 3,wherein the step of determining at least one limbal relaxing incisionposition further comprises determining a position and an orientation ofa toric intraocular lens (IOL).
 5. The software of claim 3, furthercomprising receiving outcome information for the at least one limbalrelaxing incision and updating an algorithm for determining the at leastone limbal relaxing incision based on the outcome information.
 6. Thesoftware of claim 3, wherein the astigmatism value to be treated and thecorneal power for the patient are imported from a biometer via aninterface.
 7. The software of claim 3, wherein the radial location andthe depth for the at least one limbal relaxing incision are entered by auser via a user interface.
 8. The software of claim 3, wherein theradial location and the depth for the at least one limbal relaxingincision are retrieved from surgeon-specific parameters stored in amemory.